1. Field of the Invention
The present invention relates to an orbiting scroll, and more particularly, to a rotation preventing member of a scroll compressor.
2. Description of the Related Art
Generally, a compressor is an apparatus for compressing fluid such as a refrigerant gas, and may be classified into a rotary compressor, a reciprocating compressor, a scroll compressor, etc. according to a fluid compression method.
This scroll compressor indicates a compressor of a high efficiency and low noise, the compressor widely applied to an air conditioning system. In this scroll compressor, a plurality of compression chambers are formed between two scrolls as the two scrolls perform an orbital motion with respect to each other. While continuously moving toward the center, these compression chambers have a deceased volume. Accordingly, a refrigerant is sucked, compressed and then is discharged.
FIG. 1 is a longitudinal sectional view illustrating one example of a scroll compressor in accordance with the conventional art, and FIG. 2 is a perspective view illustrating a state that an Oldham's ring has been separated from a main frame and an orbiting scroll of FIG. 1.
As shown, in the conventional scroll compressor, a main frame 2 and a sub frame 3 are disposed at an inner space 11 of a casing 1 with a predetermine gap therebetween in a horizontal direction. A driving motor 4 for generating a rotational force is installed between the main frame 2 and the sub frame 3. To the center of a rotor 42 of the driving motor 4, coupled is a crankshaft 5 passing through the main frame 2, and configured to transmit a rotational force of the driving motor 3 to an orbiting scroll 7 to be later explained by being coupled thereto. The main frame 2 is forcibly-coupled to the casing 1, and the sub frame 3 is integrally formed with the casing 1.
A fixed scroll 6 is fixedly-installed above the main frame 2, and the orbiting scroll 7 is coupled to the fixed scroll 6 to form a pair of compression chambers (P) which consecutively move, by being engaged with the fixed scroll 6. Between the orbiting scroll 7 and the main frame 2, installed is an Oldham's ring 8 for allowing the orbiting scroll 7 to perform an orbital motion with preventing a rotation of the orbiting scroll 7.
A suction pipe 12 and a discharge pipe 13 are coupled to the casing 1. The suction pipe 12 is directly communicated with a suction ort (not shown) via the casing 1, whereas the discharge pipe 13 is communicated with the inner space 11 of the casing 1. A discharge port 63 of the fixed scroll 6 for containing therein a discharge refrigerant is communicated with the inner space 11 of the casing 1.
A shaft accommodating hole 21 for supporting a crankshaft 5 in a radius direction is formed at the center of the main frame 2, and a first bearing 22 for supporting the crankshaft 5 in a radius direction is installed at the shaft accommodating hole 21.
The crankshaft 5 is forcibly-inserted into the rotor 42 of the driving motor 4, and upper and lower sides thereof are supported by the main frame 2 and the sub frame 3, respectively. Inside the crankshaft 5, an oil passage 51 is long formed along a shaft direction so that oil of the casing 1 may be sucked to be used to lubricate each bearing surface.
A fixed wrap 62 which forms a pair of compression chambers (P) is formed on a bottom surface of an end plate 61 of the fixed scroll 6 in an involute shape. A suction port (not shown) directly connected to the suction pipe 12 and sucking a refrigerant into the compression chambers (P) is formed on a side surface of the end plate 61. At the center of an upper surface of the end plate 61, formed is the discharge port 63 through which a compression gas compressed in the compression chambers (P) is discharged to the inner space 11 of the casing 1. On an upper surface of the fixed scroll 6, provided is a check valve 9 opening or closing the discharge port 63 and preventing backflow of a refrigerant gas.
On an upper surface of an end plate 71 of the orbiting scroll 7, an orbiting wrap is formed in an involute shape so as to form the pair of compression chambers (P) together with the fixed wrap 62 of the fixed scroll 6. At the center of a bottom surface of the end plate 71, formed is a boss portion 73 coupled to the crankshaft 5 and receiving a driving force of the driving motor 4. On an inner circumferential surface of the boss portion 73, installed is a second bearing 74 for supporting the crankshaft 5 and the boss portion 73 in a radius direction.
As shown in FIG. 2, a body of the Oldham's ring 8, a ring portion 81 is formed in a ring shape. At two sides of an upper surface of the ring portion 81, first keys 82 are radially formed so as to be slidably inserted into first key recesses 75 provided on a bottom surface of the end plate 71 of the orbiting scroll 7. At two sides of a bottom surface of the ring portion 81, second keys 83 are formed so as to be slidably inserted into second key recesses 23 of the main frame in a direction perpendicular to the first keys 82.
Unexplained reference numeral 31 denotes a third bearing for supporting the crankshaft in a radius direction, and 41 denotes a stator of the driving motor.
The conventional scroll compressor is operated as follows.
Once power is applied to the driving motor 4, the orbiting scroll 7 performs an orbital motion on an upper surface of the main frame 2 by the Oldham's ring 8 by an eccentric distance while the crank shaft 5 rotates together with the rotor 42 of the driving motor 4. And, the pair of compression chambers (P) which consecutively move are formed between the fixed wrap 62 and an orbiting wrap 72. The compression chambers (P) move toward the center by the continuous orbital motion of the orbiting scroll 7, thus to have a decreased volume. Accordingly, a refrigerant is sucked, compressed and then is discharged.
The first keys 82 and the second keys 83 of the Oldham's ring 8 disposed between an upper surface of the main frame 2 and a bottom surface of the orbiting scroll 7 are slidably inserted into the first key recesses 75 of the orbiting scroll 7 and the second key recesses 23 of the main frame 2, respectively, in a direction perpendicular to each other. This may prevent the orbiting scroll 7 having received a rotational force of the driving motor 4 from rotating with respect to the fixed scroll 6.
However, in the conventional scroll compressor, processing the Oldham's ring 8 is difficult due to the first keys 82 and the second keys 83. Besides, the first key recesses 75 and the second key recesses 23 for slidably inserting the first keys 82 and the second keys 83 have to be formed at the orbiting scroll 7 and the main frame 2, respectively. This may increase the fabrication costs of the orbiting scroll 7 and the main frame 2.
Besides, since the orbiting scroll 7 is supported by the main frame 2 by the first keys 82 and the second keys 83 of the Oldham's ring 8, a supportable area may be narrowed. If a tilting moment may occur at the orbiting scroll 7, the Oldham's ring 8 may be easily inclined to tilt the orbiting scroll 7. This may lower the stability and the performance of the scroll compressor, and may increase partial frictions and noise between the orbiting scroll 7 and the main frame 2 or between the orbiting scroll 7 and the fixed scroll 6.